From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2 05/12] KVM: x86: fast emulate repeat string write instructions Date: Wed, 03 Aug 2011 11:10:43 +0300 Message-ID: <4E390283.6050106@redhat.com> References: <4E37DA49.1040000@cn.fujitsu.com> <4E37DADE.1070306@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , LKML , KVM To: Xiao Guangrong Return-path: Received: from mx1.redhat.com ([209.132.183.28]:11213 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063Ab1HCIKs (ORCPT ); Wed, 3 Aug 2011 04:10:48 -0400 In-Reply-To: <4E37DADE.1070306@cn.fujitsu.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/02/2011 02:09 PM, Xiao Guangrong wrote: > We usually use repeat string instructions to clear the page, for example, > we call memset to clear a page table, stosb is used in this function, and > repeated for 1024 times, that means we should occupy mmu lock for 1024 times > and walking shadow page cache for 1024 times, it is terrible > > In fact, if it is the repeat string instructions emulated and it is not a > IO/MMIO access, we can zap all the corresponding shadow pages and return to the > guest, then the mapping can became writable and we can directly write the page > This isn't needed if we zap before emulating, right? -- error compiling committee.c: too many arguments to function